/*
 * Copyright © 2021, 2022, 2023 Peter Doornbosch
 *
 * This file is part of Kwik, an implementation of the QUIC protocol in Java.
 *
 * Kwik is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your option)
 * any later version.
 *
 * Kwik is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
 * more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package net.luminis.quic.client.h09;

import net.luminis.quic.QuicClientConnection;
import net.luminis.quic.QuicStream;
import net.luminis.quic.concurrent.DaemonThreadFactory;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLParameters;
import java.io.IOException;
import java.io.InputStream;
import java.net.Authenticator;
import java.net.CookieHandler;
import java.net.ProxySelector;
import java.net.http.HttpClient;
import java.net.http.HttpHeaders;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.ByteBuffer;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.*;

/**
 * A HTTP client for HTTP 0.9 requests.
 * See
 * <ul>
 * <li>https://www.w3.org/Protocols/HTTP/AsImplemented.html</li>
 * <li>https://superuser.com/questions/1504500/what-is-http-0-9-request</li>
 * </ul>
 */
public class Http09Client extends HttpClient {

    private final QuicClientConnection quicConnection;
    private final boolean with0RTT;
    private final int connectionTimeout = 10_000;
    private final ExecutorService executorService;

    public Http09Client(QuicClientConnection quicConnection, boolean with0RTT) {
        this.quicConnection = quicConnection;
        this.with0RTT = with0RTT;

        executorService = Executors.newCachedThreadPool(new DaemonThreadFactory("http09"));
    }

    @Override
    public Optional<CookieHandler> cookieHandler() {
        return Optional.empty();
    }

    @Override
    public Optional<Duration> connectTimeout() {
        return Optional.empty();
    }

    @Override
    public Redirect followRedirects() {
        return null;
    }

    @Override
    public Optional<ProxySelector> proxy() {
        return Optional.empty();
    }

    @Override
    public SSLContext sslContext() {
        return null;
    }

    @Override
    public SSLParameters sslParameters() {
        return null;
    }

    @Override
    public Optional<Authenticator> authenticator() {
        return Optional.empty();
    }

    @Override
    public Version version() {
        return null;
    }

    @Override
    public Optional<Executor> executor() {
        return Optional.empty();
    }

    @Override
    public <T> HttpResponse<T> send(HttpRequest request, HttpResponse.BodyHandler<T> responseBodyHandler) throws IOException, InterruptedException {
        AsyncHttpRequest<T> requestTask = new AsyncHttpRequest<>(request, responseBodyHandler);
        requestTask.run();
        try {
            return requestTask.get();
        } catch (ExecutionException e) {
            if (e.getCause() instanceof IOException) {
                throw (IOException) e.getCause();
            }
            else {
                throw new IOException(e);
            }
        }
    }

    @Override
    public <T> CompletableFuture<HttpResponse<T>> sendAsync(HttpRequest request, HttpResponse.BodyHandler<T> responseBodyHandler) {
        AsyncHttpRequest<T> future = new AsyncHttpRequest<>(request, responseBodyHandler);
        future.start();
        return future;
    }

    @Override
    public <T> CompletableFuture<HttpResponse<T>> sendAsync(HttpRequest request, HttpResponse.BodyHandler<T> responseBodyHandler, HttpResponse.PushPromiseHandler<T> pushPromiseHandler) {
        // HTTP 0.9 does not support server push
        throw new UnsupportedOperationException();
    }

    private class AsyncHttpRequest<T> extends CompletableFuture<HttpResponse<T>> {
        private final HttpRequest request;
        private final HttpResponse.BodyHandler<T> responseBodyHandler;
        private QuicStream httpStream;

        public AsyncHttpRequest(HttpRequest request, HttpResponse.BodyHandler<T> responseBodyHandler) {
            this.request = request;
            this.responseBodyHandler = responseBodyHandler;
        }

        /**
         * Run this request asynchronously.
         */
        public void start() {
            executorService.submit(() -> run());
        }

        /**
         * Run this request synchronously.
         */
        public void run() {
            try {
                complete(send(request, responseBodyHandler));
            }
            catch (IOException | RuntimeException | InterruptedException ex) {
                completeExceptionally(ex);
            }
            catch (Exception ex) {
                completeExceptionally(ex);
            }
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            httpStream.closeInput(9);  // HTTP 0.9 does not define error codes for QUIC streams
            return super.cancel(mayInterruptIfRunning);
        }

        private <T> HttpResponse<T> send(HttpRequest request, HttpResponse.BodyHandler<T> responseBodyHandler) throws IOException, InterruptedException {
            String requestPath = request.uri().getPath();
            String httpGetCommand = "GET " + requestPath + "\r\n";
            httpStream = null;

            if (!quicConnection.isConnected()) {
                String alpn;
                if (quicConnection.getQuicVersion().isV1V2()) {
                    alpn = "hq-interop";
                } else {
                    String draftVersion = quicConnection.getQuicVersion().getDraftVersion();
                    alpn = "hq-" + draftVersion;
                }

                if (with0RTT) {
                    QuicClientConnection.StreamEarlyData earlyData = new QuicClientConnection.StreamEarlyData(httpGetCommand.getBytes(), true);
                    httpStream = quicConnection.connect(connectionTimeout, alpn, null, List.of(earlyData)).get(0);
                }
                else {
                    quicConnection.connect(connectionTimeout, alpn, null, null);
                }
            }
            if (httpStream == null) {
                boolean bidirectional = true;
                httpStream = quicConnection.createStream(bidirectional);
                httpStream.getOutputStream().write(httpGetCommand.getBytes());
                httpStream.getOutputStream().close();
            }

            HttpResponse.BodySubscriber<T> bodySubscriber = responseBodyHandler.apply(new HttpResponse.ResponseInfo() {
                @Override
                public int statusCode() {
                    return 200;
                }

                @Override
                public HttpHeaders headers() {
                    return HttpHeaders.of(Collections.emptyMap(), (u, v) -> true);
                }

                @Override
                public Version version() {
                    return null;
                }
            });

            bodySubscriber.onSubscribe(new Flow.Subscription() {
                @Override
                public void request(long n) {}

                @Override
                public void cancel() {}
            });

            InputStream inputStream = httpStream.getInputStream();
            while (true) {
                int available = inputStream.available();
                if (available == 0) {
                    available = 1;  // Wait for more data
                }
                byte[] buffer = new byte[available];
                int read = inputStream.read(buffer);
                if (read < 0) {
                    break;
                }
                bodySubscriber.onNext(List.of(ByteBuffer.wrap(buffer, 0, read)));
            }
            bodySubscriber.onComplete();

            try {
                T body = bodySubscriber.getBody().toCompletableFuture().get();
                return new HttpResponseImpl(request, body);
            } catch (ExecutionException e) {
                throw new IOException(e);
            }
        }
    }
}